Conventional liners are coverings used to protect a surface from wear, corrosive materials, adhering materials, or the like. Such liners can be used in any of a variety of commercial, industrial, and residential applications. Examples may include lining various material handling or transportation equipment surfaces, such as vehicle beds and tanks; railroad car beds and tanks; decks; construction equipment, such as buckets, conveyors, scrapers, or the like; mining equipment, such as screening media, lip liners, tube covers, side rails, and chute liners; farm equipment; or the like; or lining various bulk material storage areas, such as silos, chutes, bins, storage tanks, or the like.
Such liners most typically take one of two primary forms: (1) mechanically affixed liners and (2) spray-on or dip-applied coating liners. Consistent with the above-described purposes, mechanically affixed liners are often made of metal, plastic, wood, fiberglass, ultra-high molecular weight polyethylene material, and/or other like materials. Most often, such liners are permanently affixed to the substrate material or underlying product through attachment means such as adhesive(s), nails, screws, bolts and nuts, staples, mechanical cleats, magnetic means, or the like. Alternatively, it is common in the industry to apply a semi-permanent or permanent spray-on or dip-applied coating to a base material, in order to obtain a liner with advantageous properties.
For example, commercial liners for bulk storage uses may sometimes involve application of a permanent or semi-permanent, spray-on or dip-applied coating. Some such coatings are surface coatings only; some may chemically bond to the substrate material. Illustratively, in commercial mixers, the liner may be applied to the mixing tank surface; and in storage tank vessels, the liner may be applied to the tank walls. Advantageously, such liners tend to be relatively thin, lightweight, and cost effective to apply. The benefits of such liners to the end-user may include reduced-sticking of a contained material, and easier or more effective cleaning of the container, both of which may further result in a higher yield of the contained or stored product, a more cost effective process, and/or a cleaner or more sanitary process.
Disadvantageously, however, after a period of time, whether soon after heavy use, or after a few years of prolonged use, the spray-on type liner often begins to corrode, chip, spall, or peel away. The only viable solution is to remove and reapply the coating, resulting in downtime and additional expense to the user.
On the other hand, there exist various mechanically affixed liners, and, depending upon the materials used, and upon the intended application, these liners may provide benefits such as resistance to impact (including dent and scratch resistance), and resistance to puncture, corrosion, weather, ultraviolet light, ozone, biocontaminants (such as algae), chemicals, thermal extremes, or the like. Whether alternatively or in conjunction with the above-described benefits, such liners may further provide beneficial characteristics including impermeability, low or high surface friction, elasticity, rigidity, hardness, water tightness, and greater load bearing capacities, strength, toughness, and durability. Accordingly, such liners are often used in bulk storage areas in order to take advantage of one or more of the aforementioned beneficial characteristics, such as ease of cleaning, impermeability, corrosion resistance, impact resistance, and strength.
Presently emerging in the industry are thoughts of using ultra-high molecular weight polyethylene materials and polyurethane rubber materials in liners, due to certain desirable characteristics, including low permeability, high durability and impact resistance, and, depending upon the material and formulation, low or high surface friction characteristics. For example, ultra-high molecular weight polyethylene material exhibits low frictional characteristics and is, therefore, desirable for use in applications requiring a slick, non-stick surface. Polyurethane rubber materials exhibit high durability and resistance, and desirable moldability and shaping characteristics.
Thus, while beneficial and useful characteristics in certain important applications, these very same characteristics create a challenge for use as a removable liner. Specifically, UHMWPE material cannot easily be used as a removable liner. This is because UHMWPE material cannot be conveniently attached to a substrate without damage to the underlying substrate and to the liner, in large part due the physical properties of UHMWPE material. Specifically, and as discussed above, UHMWPE material is a low friction material and, therefore, adhesives will not adhere. Furthermore, thermal welding is difficult/impractical with the current state of manufacturing process technology. Likely for these reasons, there are no known easily removable liners utilizing UHMWPE material.
Specifically, available processes require mechanical attachment to the underlying substrate, often requiring modification of, or permanent structural change to, both the substrate and liner. For example, in the prior art, it is known to use brackets, cleats, and “nuts and bolts” to attach a liner sheet to a substrate material. Specifically, the prior art discloses the use of a protective liner retainer in combination with a panel attachment member to secure the retainer to a cargo panel of a cargo bed or other material handling bin, a liner attachment member with cleats for securing a protective liner to the retainer, and a support member for attaching the liner attachment member to the panel attachment member and for defining the thickness of liner that may be secured by the retainer by separating the panel attachment member and the liner attachment member. It is also contemplated in the prior art to attach brackets to the storage area via magnetizing with continuous use of cleats. However, no specific teaching is made for a removable liner that is bracket and cleat free.
It is apparent in the prior art that use of UHMWPE material as a liner for bulk storage requires substantial modification to the substrate material in order to use. Specifically, to attach the UHMWPE material, the present options in the prior art include drilling of holes, tapping of holes, addition of mechanical elements (such as brackets, cleats, screws, nuts and bolts, and the like) to the substrate material. As a result, the UHMWPE liners are not easily removable, and mere installation results in damage to the liner and/or the substrate. Furthermore, problems with use of the aforementioned connection means includes, corrosion, stress cracks, breakage, catching of stored materials, difficulty in cleaning, cross-contamination of contained product, and the like.
In sum, then, liners in the prior art require an extensive amount of effort to install and remove. Also, due to the means of attachment, damage to the substrate material may occur. This damage includes initial modification of the substrate surface to provide attachment points, with attendant scratching, gouging, holes, rusting, cracking, water penetration and damage, contained product seepage, contamination, draw-down, or the like.
Further disadvantageously, such liners in the prior art are prone to frequent replacement issues. Specifically, when the liners are installed using conventional nut and bolt attachment means, or the like, the liner material experiences an increased level of stress in focused portions of the UHMWPE material, which may result in stress cracking. Therefore, there is increased risk that the user will have to constantly replace the liner, resulting in additional and unnecessary costs to the user.
It is apparent that an industrially-viable, easily removable liner has not been contemplated in the prior art, especially with regard to the use of UHMWPE and polyurethane rubber materials, which can be applied to a substrate material without modification of the substrate material. Due to the widespread use of ferrous metals within industrial substrates, there is now presented an opportunity to develop a liner having novel means of attachment, while taking advantage of certain desirable, inherent properties of the selected liner materials, in order to provide a liner that is easily manufactured, easily applied, easily used, easily removed, and easily replaced; all without requiring deleterious modification of the substrate material and, thereby, avoiding or obviating the above-discussed attendant disadvantages of such deleterious attachment methods.
Therefore, what is needed in order to address the above-noted disadvantages and opportunities, but which has not heretofore been available, is a novel, removable, magnetically-affixed liner comprising ultra-high molecular weight polyethylene or polyurethane rubber materials, and related processes for producing, installing, and using said magnetic, removable liner. The liner is preferably configured so that the magnetic attachment means is not easily removed or dislodged from the liner, regardless of liner material choice. It is to such desirable ends that the following developments are presented.